1. Technical Field
The present disclosure is directed to detecting the presence and positioning of user-controlled objects in an area of interest and, more particularly, to a system and method of optically sensing the presence and movement of an object or objects, such as one or more fingers or a stylus in a virtual working area to virtually control one or more electronic devices.
2. Description of the Related Art
User input devices, such as the ubiquitous computer mouse, have been used for decades as interfaces for computers and other electronic apparatus. Typically, these interface devices provide input signals to the computers via hared wired or wireless connections to control the display of a cursor on a screen. As the user moves the mouse on a surface, corresponding movement of the cursor on the display device is visually perceived. In addition, a user can select displayed items on the screen via positioning of the cursor over the displayed item and actuating one or more switches on the mouse.
With the development of touch-screen interfaces, single-touch and multi-touch input methods have become more common. For example, the user physically taps the touch-screen interface to select an object displayed on the screen. The multi-touch input methods include zoom-in and zoom-out by moving two fingers diagonally away or towards each other, respectively.
With the popularity of the multi-touch inputs, many devices have begun to include multi-touch features. For example, prominent operating systems enable multi-touch user input in association with a variety of electronic devices. Following this trend, many computer and hand held device screens have multi-touch capability. Many of the devices that utilize touch-screens are designed to be portable and easy to use, and as such they often do not include keyboards to minimize device size.
However, many of the applications that are designed to be used on these devices are easier to operate with a separate user input device, such as a mouse or keyboard. Several patents address these separate user input devices. In U.S. Pat. No. 7,215,327 issued to Liu et al. entitled “Device and Method for Generating a Virtual Keyboard/Display,” a scanning laser light source having a first laser emitter and a second laser emitter scans a surface to determine a user's movements and selection. The device receives a first and a second reflected beam and determines a time difference for each beam from an initial scanning point to a final scanning point. The device then determines the user's coordinates by comparing the two scan time differences of the first and second reflected beams.
In U.S. Pat. No. 6,710,770 B2 issued to Tomasi et al. entitled “Quasi-three-dimensional Method and Apparatus to Detect and Localize Interaction of User-Object and Virtual Transfer Device” a virtual keyboard and input device is provided. A first light system OS1 projects a beam of light parallel to a surface. A second light system OS2 works with the first light system OS1 to determine a location of an object crossing the beam of light. This patent includes an active triangulation detection method using the first light system OS1 to project the beam and the second light system OS2 as a camera. This patent also includes a passive triangulation method where both the first and second light systems OS1 and OS2 are cameras. Both the active and passive methods use homography to transform an image of an object intersecting the beam to relay the object's actual location in the real world to an associated electronic device. In addition, the cameras OS1 and OS2 can be configured to detect color in order to counteract problems with ambient light.